1. Field of the Invention
The present invention relates to a storage element.
2. Description of the Related Art
Electronic components now need to become even smaller as devices shrink and become denser. One known example of this is a storage element that can control electrical resistance by applying voltage between two electrodes separated by a minute gap (nanogap).
Such storage elements are constituted such that a nanometer order gap (for example, 10 nm or less) is provided between electrodes, and by electrically changing the separation distance of this gap, a tunnel current between the electrodes is controlled. The tunnel current changes greatly even if the separation distance of the gap between the electrodes (electrode gap) changes by only about 0.1 nm, but the shape of the electrode surface that determines the separation distance of the electrode gap is vulnerable to the effects of the state of the gas within the electrode gap, so the electrode gap must be hermetically sealed in order to increase its operating stability. Proposals to this end include encapsulating the entire storage element in a sealing material, installing a sealing dielectric that covers the electrode gap and maintains it without plugging it, and covering the aperture portion of a hole that exposes a portion of one of the two electrodes (first electrode) with the other electrode (second electrode) (for example, see Japanese Patent Application Laid-Open Publication No. 2008-243986).
There are problems, however, including: when the entire storage element is encapsulated with a sealing material in order to hermetically seal the electrode gap, a vacuum must be created inside the sealing material, for example; when a sealing dielectric is installed that covers the electrode gap and maintains it without plugging it, the sealing dielectric must be formed within a vacuum state, for example; and when covering the aperture portion of a hole that exposes a portion of the first electrode with the second electrode, the second electrode must be formed within a vacuum state, for example. Because there are limits to how great a vacuum can be formed using a vacuum pump or the like, however, the electrode gap cannot be hermetically sealed in a reliable manner.
Furthermore, with a conventional storage element such as that described in Japanese Patent Application Laid-Open Publication No. 2008-243986, the electrode gap is hollow, so there is the problem of difficulty forming electrode gaps with the desired separation distance with good reproducibility because of the effects of manufacturing disparities.